A novel cyclophane compound, CPPy, facilitates NGF-induced TrkA signal transduction and induces cell differentiation in neuroblastoma.

Neuroblastoma (NB) often causes spontaneously regression, and can mature to ganglioneuroma. The form with the most favorable prognosis expresses high levels of TrkA, a high-affinity receptor for nerve growth factor (NGF), whereas advanced NB and associated cell lines have abnormalities in the NGF/TrkA signaling pathway. A novel cyclophane, cyclophane pyridine (CPPy), was designed to conserve the tyrosine phosphorylation of TrkA, thereby enhancing NGF/TrkA signal transduction. We investigated whether this compound improved NGF-induced tyrosine phosphorylation of the Y490 domain of TrkA and conserved the expression of an early gene (c-fos) in human NB cell lines (IMR-32 and NB-39). As determined by Western blotting, TrkA (Y490) phosphorylation was enhanced by the combination of CPPy (10(-8) M) and NGF (100 ng/ml) compared with NGF alone. CPPy also conserved NGF-induced c-fos mRNA expression. Moreover, CPPy induced the morphological differentiation of NB cells, leading to expression of the neuronal marker gene GAP-43. These data suggest that CPPy can induce the differentiation of NB cell lines by facilitating NGF-induced TrkA/Ras/MAPK signal transduction, and may therefore be an effective therapeutic agent for NB.